Originally an IMAX 3D film and now appearing on DVD and Blu-ray, Under The Sea spends 41 minutes transporting the viewer to the Coral Triangle and Great Barrier Reef of the South Pacific to witness what life is like there. Narrated by a restrained Jim Carrey, this film is a sequel of sorts to director Howard Hall's previous IMAX hit, Deep Sea, as we see creatures going about their routines of eating, procreating, and surviving.
In high definition the footage looks amazing and anyone who enjoys watching nature films will enjoy the many highlights. As a large school of striped catfish eats algae off the floor, they resemble a wave rolling along as the back row continuously jumps to the front. An even larger school of baby convict fish seems to impossibly funnel into a burrow. A field of garden eels, some as high as six feet, sway in the current-like crops in a windy field. We see a number of creatures eat, but the most compelling is a turtle make a meal out of a jellyfish. The footage indicates the fish pay no attention to the camera, but a group of Australian sea lions are very curious about what they are doing.
About 25 minutes in, the purpose of the film is made clear as we get a global-warming message about changing ocean temperatures and the effect on coral reefs. Carrey also talks about the "changes we are causing to our atmosphere, our oceans, and our planet" that lead to ocean acidification from too much carbon dioxide and eventual extinction. It's not heavy-handed but is unexpected.
The IMAX film was given a 1080p/VC-1 encoded transfer and a 1.85:1 aspect ratio. The colors are very vivid, both under the water and above it. There's depth to be seen even without special glasses, and textures close up are very finely detailed. The audio DTS-HD Master Audio 5.1 immerses the viewer among the ocean effects of volcanic gasses and movement of the fishes. Jim Carrey's narration is clear and comes out the front speakers, mainly the center channel with support from the sides. There is some directionality as larger creatures move about. Effects added later such as the crunching of crab shell and a loud smooch from a sea lion sound inauthentic. The bass adds subtle presence to the soundtrack. The film is subtitled in English SDH, French, Spanish, and Dutch.